Refrigeration appliance and method for the operation thereof
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Solution Overview
Problem
Existing refrigeration devices with multiple temperature zones struggle to maintain stable temperature control due to unsatisfied cooling demands leading to undesirable temperature fluctuations, as existing systems redistribute cooling capacity without accounting for changing cooling requirements across zones.
Innovation Solution
A refrigeration device with a compressor, evaporators, and controllable throttle points, where the first controllable throttle point is upstream of the first evaporator and downstream of the second evaporator, allowing independent control based on the second temperature zone's temperature, and a compressor controller adjusts speed based on the first temperature zone's requirements to decouple and stabilize cooling capacity distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the throttling on the controllable expansion valve upstream of the evaporator in a temperature zone is increased to satisfy unsatisfied cooling requirement, then the evaporation temperature in the relevant evaporator decreases and cooling capacity in this temperature zone increases, but the mass flow of the refrigerant in the refrigerant circuit remains unchanged overall and cooling capacity must be withheld from other temperature zones
Solution Approach 1:
The patent changes the controlling parameter from downstream evaporator temperature to upstream evaporator temperature. By measuring the temperature at the inlet of the first evaporator (upstream) and using it to control the expansion valve opening, the system can adjust refrigerant flow to meet cooling demands in the first temperature zone without being constrained by feedback from downstream zones, thereby resolving the contradiction between satisfying local cooling requirements and maintaining overall cooling capacity distribution.
2Stability of the object's composition
If the throttling in an expansion valve downstream of the relevant evaporator is reduced in return to prevent affecting other evaporators, then the throttling of the expansion valves connected in series remains unchanged and mass flow remains unchanged, but the available cooling capacity must be withheld from other temperature zones
Solution Approach 1:
The patent extracts the temperature measurement point from the downstream location (after the evaporator) and places it upstream (at the inlet of the first evaporator). This extraction allows the control system to independently adjust the expansion valve based on actual cooling needs at the evaporator inlet, separating the control of mass flow from the cooling demand response, thereby enabling cooling capacity to be allocated to temperature zones without compromising overall mass flow stability.
3Adaptability or versatility
If cooling capacity is redistributed to satisfy unsatisfied cooling demand in another temperature zone, then temperature control in the first temperature zone is affected, but this leads to undesirable temperature fluctuations and inability to take into account changing cooling requirements of all temperature zones
Solution Approach 1:
The patent implements a feedback control mechanism where the temperature at the inlet of the first evaporator is continuously measured and used to adjust the opening of the first expansion valve. This upstream temperature feedback allows the system to adapt to changing cooling requirements in real-time while maintaining temperature stability in the first temperature zone, as the control action is taken at the point where it most directly affects the cooling process before refrigerant enters the evaporator.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables simple and stable temperature control across zones by independently adjusting the first controllable throttle point and compressor speed, effectively compensating for changes in cooling demand, reducing temperature fluctuations, and maintaining energy efficiency.
Implementation Method 1
a compressor (10) and a controllable expansion valve (20, 21, 18')
Implementation Method 2
a first evaporator (6) for cooling the first temperature zone (1) and a second evaporator (7) for cooling the second temperature zone (2)
Implementation Method 3
a first controllable throttle point (20, 21, 18') in the refrigerant circuit is connected upstream of the first evaporator (6) and downstream of the second evaporator (7)
Data Source
Figure 1~3
Figure 4~5
AI summary
A refrigeration appliance comprises at least a first and a second temperature zone (1, 2) and a refrigerant circuit that includes a compressor (10), a first evaporator (6) for cooling the first temperature zone (1) and a second evaporator (7) for cooling the second temperature zone (2). The first evaporator (6) is serially connected downstream of the second evaporator (7) in the refrigerant circuit, and a controllable throttle point (21) is arranged upstream of the first evaporator (6) and downstream of the second evaporator (7) in the refrigerant circuit. A controller (28) controls the opening degree of the controllable throttle point (21) on the basis of the temperature in the second temperature zone (2) and independently of the temperature in the first temperature zone (1).